Some great materials about the unauthorized "chevron" mark on the first M9s.
This is the first time I see a document about this.
Interesting to note, from the second picture, is Quantity:
1.080
From this site "
One hundred sixty-six pieces of the 1200 piece run had not been shipped and these were held back".
There seems to be a discrepancy:
1200-1080= 120